Pressure shut-off valve units of this type may be used, for example, in the form of individual valves or as valve combinations in the inlet region of tanks or tank systems of motor vehicles in order to prevent overfilling of the pressure accumulator vessel with fuel during a replenishing or filling operation. After the filling operation, the fuel has to be removed again for consumption. Various valve combinations are known for this purpose.
A shut-off valve is known from U.S. Pat. No. 3,709,241. In the case of this valve, a piston is guided in a bore in a valve body in order to limit the filling pressure in a tank. The piston has an elastic sealing element and is pressed against a constricted inlet opening by a spring. Between the bore of the valve body and the piston there is a gap through which gas may pass from the outlet region of the valve into a region of the bore behind the piston, and therefore, the pressure in the outlet region exerts an axial force on the piston and thus supports the spring in the closing of the inlet opening. Gas is thus prevented from flowing from the outlet region back to the inlet opening and at the same time the filling pressure is prevented from exceeding a predetermined value. A removal of gas is not provided with this shut-off valve.
In addition, it is known that a filling pressure of a pressure accumulator vessel or a pressure accumulator system may be controlled and limited by measuring the pressure and by electronic control of electric valves.
European Patent Publication No. EP 1 855 048 B1 discloses a valve arrangement for a gas vessel, the valve arrangement being arranged on the gas vessel, having: a carrying-away line of a gas, which makes it possible for the inside of the gas vessel to communicate with the outside; a first gas line which makes it possible for the inside of the gas vessel to communicate with the outside, and which differs from the carrying-away line; a valve which is on the carrying-away side and which is arranged on the carrying-away line and is configured in such a manner that it blocks the carrying-away line; a first valve which is arranged on the first gas line and is configured in such a manner that it blocks the first gas line; a communication path which connects a section of the carrying-away line outside the gas vessel, as viewed from the valve on the carrying-away side, to a section of the first gas line in the gas vessel, as viewed from the first valve; and a communication shut-off mechanism which opens and closes the communication path, characterized in that the communication shut-off mechanism is configured in such a manner that it opens the communication path, as a result of which the gas accumulated in the gas vessel flows through the first gas line, the communication path and the carrying-away line in this sequence, wherein the first gas line is a filling line which fills the gas vessel with the gas.
European Patent Publication No. EP 1 855 048 B1 is representative of a number of combined valve arrangements which make it possible for fluids to be filled into and removed from pressure accumulator vessels. However, in the applications mentioned, it is desirable for a permissible operating pressure of a pressure accumulator vessel or a pressure accumulator system to be reliably maintained during a filling operation and thus to ensure the maximum operating safety. The filling operation is intended to be able to be carried out as rapidly as possible and with only low energy losses. Wear to valve components is intended to be kept low and damage to pressure accumulator vessels and pressure lines is intended to be prevented. In addition, it is desirable to simplify the pipework of the pressure accumulator systems and to reduce the number and complexity of the pressure lines.